Stochastic modeling of seismic surface rotations

In this paper, a stochastic analysis of surface rotations during earthquakes is presented. The surface motion is modeled by a spacetime random field. A method to obtain rotation based on direct differentiation of the random field is proposed with a reference to a second method based on wave decomposition. The first method leads to a spectral density of surface rotations in terms of point translation spectral density, coherence function and apparent waves velocity, while the second method formulates the rotational spectrum in terms of point translation spectral density and wave parameters. The advantages and disadvantages of both methods are discussed in detail.On leave from: Faculty of Civil Engineering, Technical University, ul. Katowicka 48, 45–951 Opole Poland.     

Distribution of time lags between successive petroleum exploration activities

Four time lags are studied: (1) drilling activity behind seismic activity; (2) oil and gas reserves discovered behind drilling activity; (3) oil and gas production behind reserves discovered; and (4) oil and gas production behind drilling activity. A ridge regression method is used to estimate the distributions of these lags for 50 countries and regions active in petroleum exploration. A complete review of obtained results is given as well as an interpretation of estimated models and failed ridge regressions. Five types of distributions have been found: decreasing monotonically, unimodal, bimodal, uniform, and increasing monotonically. The distributions allow estimating the capital freezing in the exploration process and assessing the resulting policy made by all companies active in a country. For example, the actual exploration history in Poland is analyzed with the use of distributed time-lag approach and net present-value concept. An overinvestment in drilling in comparison with petroleum infrastructure has been stated on the basis of the excessive lagging of production behind drilling activity. A direction of further lag studies is also suggested.     

Fourth international symposium on land subsidence Houston,Texas, USA 12–15 May 1991

Fourth international symposium on land subsidence Houston, Texas, USA 12–15 May 1991     

On reconstruction of the Ito-like equation from persistent time series

The Langevin equation with finite-range persistence was introduced as a macroscopic model of various geophysical phenomena. The modified histogram procedure (MHP) of reconstruction of the equation from time series was proposed. An efficiency of MHP was tested on artificial persistent time series (with short and long-tail distributions) generated by different Ito-like equations. For an exemplary geophysical time series, the appropriate Ito-like equation was reconstructed.     

Changes of snow cover in Poland

The present paper examines variability of characteristics of snow cover (snow cover depth, number of days with snow cover and dates of beginning and end of snow cover) in Poland. The study makes use of a set of 43 long time series of observation records from the stations in Poland, from 1952 to 2013. To describe temporal changes in snow cover characteristics, the intervals of 1952–1990 and of 1991–2013 are compared and trends in analysed data are sought (e.g., using the Mann–Kendall test). Observed behaviour of time series of snow-related variables is complex and not easy to interpret, for instance because of the location of the research area in the zone of transitional moderate climate, where strong variability of climate events is one of the main attributes. A statistical link between the North Atlantic Oscillation (NAO) index and the snow cover depth, as well as the number of snow cover days is found.     

What can we learn from the projections of changes of flow patterns? Results from Polish case studies

River flow projections for two future time horizons and RCP 8.5 scenario, generated by two projects (CHASE-PL and CHIHE) in the Polish-Norwegian Research Programme, were compared. The projects employed different hydrological models over different spatial domains. The semi-distributed, process-based, SWAT model was used in the CHASE-PL project for the entire Vistula and Odra basins area, whilst the lumped, conceptual, HBV model was used in the CHIHE project for eight Polish catchments, for which the comparison study was made. Climate projections in both studies originated from the common EURO-CORDEX dataset, but they were different, e.g. due to different bias correction approaches. Increases in mean annual and seasonal flows were projected in both studies, yet the magnitudes of changes were largely different, in particular for the lowland catchments in the far future. The HBV-based increases were significantly higher in the latter case than the SWAT-based increases in all seasons except winter. Uncertainty in projections is high and creates a problem for practitioners.     

Robustness of Msplit(q) estimation: A theoretical approach

Studia Geophysica et Geodaetica - Msplit(q) estimation is a development of M-estimation which is based on the assumption that a functional model of observations can be split into q competitive...     

On the vertical distribution of passive species in the atmospheric boundary layer

A similarity theory presented by Sorbjan (1986) is extended by taking into consideration diffusion of passive species (e.g., specific humidity) in the atmospheric boundary layer. Theoretical similarity functions are obtained for the convective and stable-continuous regimes.On leave from Institute of Environmental Engineering, Warsaw Technical University, Poland.